Water-in-oil emulsions are well known in the cosmetic art. While it is possible to prepare clear water-in-oil emulsions, these are generally "ringing gel" type microemulsions containing high levels of surfactants, e.g. 40-50%. They cannot be thinned down to flowable lotions without becoming opaque. Furthermore, these gels are generally heavy, sticky, tacky gels, and therefore, are cosmetically undesirable. The emulsifiers used to prepare them are polyhydric alcohols, ethoxylated alcohols, lanolin alcohols, ethoxylated lanolins, etc. There is a preference among users of skin care products for clear tanning oils which posses a smooth, non-tacky feel upon application.
Sunscreens are well known in the cosmetic art as useful to prevent sun burn and sun exposure related irritation. Sunscreen lotions are rated according to there effectiveness using a Sun Protection Factor (SPF) on a scale of 0 to 15; 0 representing no protection and 15 representing total sun block. However, there are products marketed which have SPF values greater than 15.
In general, sunscreen products are oil in water emulsions containing about 50 to 75% water. It has not been possible, heretofore, to produce tanning oil products with a SPF of greater than six without the use of large quantities of water or other polar materials. It is believed that this is because the known sunscreen agents require the presence of a polar compound such as alcohol or water to make &hem more effective (increase SPF).
In the past, it has been necessary to use high concentrations of sunscreen agents to produce clear tanning oils with an SPF value of 6. There is an available market for such clear tanning oils, since most users of sunscreens prefer tanning oils to the conventional water based emulsions which are usually opaque white or yellowish in color. These oil-in-water emulsions of the prior art contain about 50 to 75 weight percent water; minor amounts of esters are added to improve their feel.
There is a ready market for a water-in-oil type emulsifier for emollient and other cosmetic uses, which has a dry, oily feel and spreads on with a smooth, non-tacky feel. In particular, what is needed to satisfy the demand of those who find the use of the conventional oil-in-water sunscreen emulsions objectionable, is a tanning oil containing only sufficient amounts of water to make the sunscreen agents effective, while at the same time being clear microemulsion systems with an elegant oily feel.